A search for X-ray counterparts of the millisecond pulsars in the globular cluster M28 (NGC 6626)

TL;DR

This study revisits archival Chandra X-ray data of globular cluster M28 to identify X-ray counterparts of its numerous millisecond pulsars, revealing positional coincidences with several pulsars and faint unresolved X-ray emission.

Contribution

It provides the first identification of X-ray counterparts for multiple millisecond pulsars in M28 using archival data, enhancing understanding of pulsar emission in globular clusters.

Findings

X-ray counterpart for PSR J1824-2452H identified

Faint unresolved X-ray emission near cluster center coincides with several pulsars

Positional agreement between radio and X-ray sources established

Abstract

A recent radio survey of globular clusters has increased the number of millisecond pulsars drastically. M28 is now the globular cluster with the third largest population of known pulsars, after Terzan 5 and 47 Tuc. This prompted us to revisit the archival Chandra data on M28 to evaluate whether the newly discovered millisecond pulsars find a counterpart among the various X-ray sources detected in M28 previously. The radio position of PSR J1824-2452H is found to be in agreement with the position of CXC 182431-245217 while some faint unresolved X-ray emission near to the center of M28 is found to be coincident with the millisecond pulsars PSR J1824-2452G, J1824-2452J, J1824-2452I and J1824-2452E.